P1134

Circuit Description
The powertrain control module (PCM) continuously monitors the heated oxygen sensor (HO2S) activity for 100 seconds. During the monitor period the PCM counts the number of times that the HO2S responds from rich to lean and from lean to rich and adds the amount of time it took to complete all of the transitions. With this information, an average time for all transitions may be determined. The PCM then divides the rich to lean average by the lean to rich average to obtain a ratio. If the HO2S transition time ratio is not within range, DTC P1134 is set, indicating that the oxygen sensor is not responding as expected to changes in exhaust oxygen content.

Conditions for Running the DTC
1. None of the following DTCs are present:
^ Throttle position (TP) sensor DTCs
^ Evaporative emissions (EVAP) system DTCs
^ Intake air temperature (IAT) sensor DTCs
^ Manifold absolute pressure (MAP) sensor DTCs
^ Exhaust gas recirculation (EGR) pintle position DTCs
^ Mass air flow (MAF) sensor DTCs
^ Engine coolant temperature (ECT) sensor DTCs
^ Crankshaft position (CKP) sensor DTCs
^ HO2S 1 heater circuit DTCs
^ Misfire DTCs
^ Fuel trim DTCs
^ Injector circuit DTCs
2. The MAF is between 10 g/s and 30 g/s.
3. The ECT is more than 50°C (122°F).
4. The engine run time is more than 60 seconds.
5. The engine speed is between 1000 RPM and 3000 RPM.
6. The engine is running in closed loop.

Conditions for Setting the DTC
^ The above conditions are present for a 100 second monitoring period.
^ The ratio of average response times is not between 3.5 and 0.5.

Action Taken When the DTC Sets
^ The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has run and failed.
^ The PCM stores the conditions which were present when the DTC set as Freeze Frame and Fail Records data.

Conditions for Clearing the MIL/DTC
^ The PCM turns the MIL off during the third consecutive trip in which the diagnostic has run and passed.
^ The history DTC clears after 40 consecutive warm-up cycles have occurred without a malfunction.
^ The DTC may be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.

Diagnostic Aids
A malfunction in the HO2S heater ignition feed or ground circuit may cause the DTC to set. Test the HO2S heater circuitry for intermittent malfunctions or faulty connections. If the connections and wiring are OK and the DTC continues to set, replace the HO2S 1.
Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
4. This step checks for conditions which may cause the DTC to set with a good heated oxygen sensor. Correct any of the described conditions if present.
7. Before replacing the HO2S, check for silicon contamination.